There are 70 species of Diascia endemic to southern Africa found mostly in the eastern regions including Lesotho, Free State, KwaZulu-Natal and Eastern Cape Province. Most species found in the latter are annuals.

Diascia is derived from the Greek words, di, two, and askos, sac, referring to the pair of translucent yellow sacs/windows in the corolla and not to the two spurs which are absent in the type specimen D. bergiana. Most annual Diascia species follow this example, but in the perennials, the window is single or only slightly doubled. The double spur, though, is a striking characteristic of many Diascia species. The spurs contain glandular hairs which secrete fatty oil. In some species, small dark patches of these tiny glands are also found on the face of the flower. The oil is harvested by members of a genus of bee which evolved to reach into the spurs of the flower.

It is thought that the epithet patens was given by Thunberg because of the characteristically narrow, outspread leaves of the species.

Diascia patens is related to D. capsularis and can be recognised by its 2-4.5 mm broad, narrower, linear leaves, which are not 5-17 mm broad and triangular as in D. capsularis. Other features that set D. patens apart are its shorter spurs, filaments and style.

The first collections of Diascia patens are about two hundred years old. Thunberg made the original collection, but the locality was not recorded. A second journey was made to Kaffraria, the British colony in the southeastern part of the Eastern Cape in the region of King Williams Town and East London. The Langekloof and Uniondale districts were visited during these travels where more collections were made.

Specimens by other early collectors such as Burchell and Taylor have helped solve the puzzle of the locality of Thunberg's original specimen.

Diascia was not described until 1820 and early specimens of D. patens were placed under long-established genera, such as Antirrhinum, Linaria and Nemesia, until they were appropriately classified with regard to their characteristic twin spurs.

Synonyms for Diascia patens are: Antirrhinum patens Thunb., Diascia monasca Hiern, Linaria patens (Thunb.) Spreng., Nemesia patens (Thunb.) G.Don.

Little is still known about this species even though its documentation started so many years ago.

Diascia patens `Cheeky Chief' was collected by a Kirstenbosch horticulturist, A. Harrower, in 2005. Selections based on flower colour, flower size, compactness and a long flowering season were made to bring forth this playful cultivar.